This invention relates to primate T-lymphotropic viruses, as well as assays for such viruses and substances used in those assays.
A group of closely related human retroviruses that preferentially infect helper T-lymphocytes have been designated human T-lymphotropic viruses (HTLV). One type of HTLV, designated HTLV-I, has been linked with the development of adult T-cell leukemia/lymphoma (Poiesz et al. (1980) Proc. Nat""l. Acad. Sci. USA 77:7415). A virus related to HTLV-I has been reported in non-human primates, specifically Asian and African Old World primate species, but not New World primates and prosimians. The primate viruses from baboons, African green monkeys, and Macaca species are related to, yet distinct from, HTLV-I. Guo et al. (1984) Science 223:1195; Tsujimoto et al. (1985) Virology 144:59.
Another type of HTLV, designated variously as HTLV-III, or Lymphadenopathy Associated Virus (xe2x80x9cLAVxe2x80x9d or xe2x80x9cARVxe2x80x9d) is the prototype virus from patients with acquired immune deficiency syndrome (AIDS) (Popovic et al. (1984) Science 224:497; Salahuddin et al. (1984) Science 224:500; Schupbach et al. (1984) Science 224:503; Sarngadharn et al. (1984) Science 224:506). Various antigenic proteins from HTLV-III infected cells have been reported, including:
1) a 55 kd gag polyprotein (p55) which yields a 24 kd protein (p24) as the major virus core protein, and a 17 kd phosphoprotein (pp17) (Schupbach et al. (1984) Science 224:503-505); and
2) an envelope glycoprotein (gp160) which gives rise to a 120 kd glycoprotein (gp120) at its amino terminus (Essex and Lee, U.S. Ser. No. 670,361, filed Nov. 9, 1984, and a continuation-in-part thereof filed Nov. 7, 1985, both of which are hereby incorporated by reference).
The discovery and characterization of the polypeptide of this invention are important in several respects. First, the polypeptides provide a source of antigenic determinants that are generally useful in assays of simian or human specimens, as described below. Second, African green monkeys, are used for research and development of a variety of biological reagents; for example African green monkey tissue is used in the production of oral polio vaccine. It is desirable to reduce the chance (however unlikely) that an AIDS-like disease could be transmitted inadvertently in polio vaccine or other products produced from STLV-III-infected animal tissue. Third, a vaccine based on the proteins could protect against AIDS.
Peptides Having Antigenic Determinants According to the Invention, And Assays Using Them
A first aspect of the invention generally features a substantially pure polypeptide having at least one antigenic determinant that is substantially identical to an antigenic determinant of a protein from a cell line infected with a virus deposited with the ATCC as CRL 8942, CRL 8943, or VR 2129, the protein being selected from: a glycoprotein having a molecular weight (m.w.) of about 160,000 daltons; and a glycoprotein having a m.w. of about 120,000 daltons. daltons; a gag protein having a m.w. of about 55,000 daltons; a gag protein having a m.w. of about 24,000 daltons; and a glycoprotein having a m.w. of about 32,000. By xe2x80x9ca polypeptide having an antigenic determinant that is substantially identical to a protein antigenic determinantxe2x80x9d is meant a polypeptide comprising an antigenic determinant which: a) in common with the protein antigenic determinant, will react with a given antibody; and b) is derived either by i) isolating the naturally produced protein or a fragment of it; or ii) synthesizing (e.g. by expression of DNA such as by the general method of Chang et al. (1985) Nature 315:151, or chemical synthesis) an amino acid sequence identical to the protein antigenic determinant. As demonstrated below, the polypeptides of the invention are immunologically cross-reactive with HTLV-III cell proteins, but the reaction of a polypeptide of the invention with a given antibody may vary in comparison to the reaction of the corresponding HTLV-III protein with the same antibody. Therefore, determinants of the polypeptides of the invention are not substantially identical to HTLV-III determinants.
Preferably, the polypeptide antigenic determinant is substantially identical to an antigenic determinant of a protein expressed in a cell line infected with STLV-III. Preferably, the polypeptide is one of the proteins listed above, or a fragment thereof; most preferably, the polypeptide is a gp32 or a gp160 or gp120 glycoprotein in the glycosylated or unglycosylated form. Also preferably, the polypeptide is not substantially cross-reactive with the HTLV-III/LAV glycoprotein p41; and the polypeptide antigenic determinant is more strongly reactive with an antibody capable of reacting with a determinant of a glycoprotein of one of the deposited strains than with an HTLV-III glycoprotein determinant. Other useful polypeptides which have the necessary immunogenic determinants include synthetic polypeptides.
The above described polypeptides of the first aspect of the invention are useful, among other things, for assaying for the presence of antibodies to T-lymphotropic viral antigens, by incubating a specimen with the polypeptide and determining whether or not an immunocomplex is formed. Also, the above-described polypeptides can be used to raise an antibody that is useful for assaying a biological specimen (e.g., human or simian) for the presence of an antigenic determinant that is immunologically cross-reactive with a determinant of one of the four proteins listed above. The assay is performed by incubating the specimen with the antibody thus raised and determining whether an immunocomplex is formed. The determinants to be assayed may occur on the stated proteins themselves or on other polypeptides. They may be in free circulation in the body fluids or in lymphocytes. The assay can be carried out by known immunoassay methods, using antibodies, monoclonal or polyvalent, having immune reactivity with the antigenic determinants found on the stated proteins. For example, competitive immunoassays or immunometric (sandwich) assays can be used. The assays of the first aspect are preferably performed on simian specimens, but they can also be performed on human specimens.
Vaccines
In another aspect, the invention features a vaccine comprising the above described deposited virus or a subunit protein or polypeptide thereof, such as the gp120, or gp160 or a peptide fraction of those molecules that reacts with HTLV-III. This could be presented in a pharmaceutically acceptable carrier. Vaccine could also comprise proteins from cells infected with the deposited virus or an altered form thereof.
Other features and advantages of the invention will be apparent from the following description of the preferred embodiment and from the claims.